Safety valve assembly for controlling clutch and brake in power press or the like

ABSTRACT

A valve assembly for a pressurized fluid line controlling a clutch and brake made up of a pair of valves having movable valve members with separate actuators, each of the valve members having inlet ports and outlet ports, the inlet ports being connected in series and the outlet ports being connected effectively in parallel so that both valves must be activated to pass the pressurized fluid to the control line and so that upon unwanted sticking of one of the valve members in activated position, pressure fluid to the control line is cut off and exhaust fluid from the line is promptly and directly vented.

United States Patent Mahorney [54] SAFETY VALVE ASSEMBLY FOR CONTROLLINGCLUTCH AND BRAKE IN POWER PRESS OR THE LIKE Wright., ..l37/596. 16

[ 1 June 20, 1972 Primary ExaminerHenry T. Klinksiek AssistantExaminer-Robert J. Miller Anomey-Wolfe, Hubbard, Leydig, Voit & Osann[57] ABSTRACT A valve assembly for a pressurized fluid line controllinga clutch and brake made up of a pair of valves having movable valvemembers with separate actuators, each of the valve members having inletports and outlet ports, the inlet ports being connected in series andthe outlet ports being connected effectively in parallel so that bothvalves must be activated to pass the pressurized fluid to the controlline and so that upon unwanted sticking of one of the valve members inactivated position, pressure fluid to the control line is cut off andexhaust fluid from the line is promptly and directly vented.

6 Claims, 5 Drawing Figures hill 4% SAFETY VALVE ASSEMBLY FORCONTROLLING CLUTCH AND BRAKE IN POWER PRESS OR THE LIKE It has beenrecognized in the past that use of a simple threeway valve foralternatively admitting pressurized fluid to a clutch and brake controlline in a power press, and exhausting fluid therefrom, does not provideadequate safety since sticking of the valve in its activated conditionmay prevent the slide from safely coming to rest at the top of thestroke at the completion of a press cycle. Unwanted descent of the slidemay cause a serious accident. To provide a safety factor it has beenproposed in the past that two separately actuated threeway valves beconnected in parallel with one another. Thus if one of the valves sticksin its open or activated position the fluid which is passed isharmlessly vented through the companion valve. The drawback to this isthat the flow of vented fluid is so great asto produce a condition ofpartial or back pressure in the control line so that the clutch may notbe completely disengaged nor the brake surfaces fully seated.

It has also been proposed toconnect two three-way valves effectively inseries with one another which insures shutofl' of the pressurized fluidin the event that one of the valves sticks in open position. The problemhere is that where the downstream valve is the sticking one the fluidwhich is ex hausted from the control line must be exhausted throughinlet ports, which are usually quite restricted in cross section, whichdelays venting and therefore delays de-clutching and setting of thebrake.

It is, accordingly, an object of the present invention to provide avalve assembly in which both of these undesirable conditions areobviated. More specifically it is an object of the invention to providea valve assembly having first and second separately actuated valvemembers which have inlet ports connected in series so thatpressurizedfluid cannot flow as long as at least one of the valvemembers responds to the deac' tuation and which insures prompt anddirect venting of the control line to near zero pressure withoutnecessity for the exhaustedfluid to traverse the inlet ports of eitherof the two valves.

Other objectsand advantages of the invention will become apparent uponreading the attached detailed description and upon reference to thedrawings in which:

FIG. 1 shows, in cross section, a valve assembly constructed inaccordance with the present invention and employing two separatelyactuated valve members which are both in activated" condition forpressurizing the clutch and brake control line.

FIG. 2 shows the valve assembly of FIG. 1 in deactuated condition withboth of thevalve members turned off and with the control line beingvented to the exhaust condition.

FIG. 3 shows the condition of the valve assembly with the second valvemember inadvertently stuck in open condition.

FIG. 4 shows the assembly with the first valve member stuck in opencondition.

While the invention is described in connection with a preferredembodiment, it will be understood that I do not intend to limit theinvention to the particular embodiment shown but intend, on thecontrary, to cover the various alternative and equivalent valveconstructions which are included within the spirit and scope of theappended claims.

Turning now to FIG. 1, a frame or housing 10 is provided mounting a pairof valve members 11, 12. Ports are provided in the valve housing forconnection to an air supply line 13, a control, or output, line 14, andan exhaust line 15. The valve members are, in the present instance, inthe form of spools mounted for vertical movement. Taking the spool 11 byway of example, in portion A of the valve, it has spaced, inwardlyfacing flanges 21, 22 cooperating with respectively opposed valve seats23, 24. The valve seats are spaced axially by a lesser distance than theflanges so that the valve spool is movable between limit positions, thatis, between an upper position, which will also be referred to as an"activated or on" position in which the upper seat 23 is open, and alower position, i

the upper seat 23 is sealed off. For permitting endwise movement of thevalve spool, the spool has a cylindrical projection 25 at its upper endwhich is slideable in a bore 26 as well as a cylindrical projection 27at its lower end slidable in a bore 28. The central stem of the valvespool, which is of reduced diameter, and which is indicated at 31, issnugly fitted and slideable within a central land 32.

For convenience the seats 23, 24 and central land 32 are all formed on acylindrical insert 35 which is sealed to the body or housing 10 ofthevalve by suitable O-rings. The cylindrical insert 35 is provided withsets of lateral openings 36, 37, which sets may be respectively four innumber and arranged, as shown, at two different levels. The insert 35 issealed at three levels by O-rings 38. I

For the purpose of moving the valve spool 11 to its upper or on positionas shown in FIG. 1, the lower end of the valve spool is engaged by aflexible diaphragm 40, defining below it a space41 into whichair orother pressurized fluid may be admitted through a pilot orifice 42.

The pilot orifice 42 is supplied with air or other piloting fluid from apilot valve 43 which may be connected to the same supply line 13 whichserves as the source of pressure fluid and with the valve being operatedby a solenoid 44 under the control of electrical line 45. The pilotvalve 43 and solenoid 44 will be understood to be conventional andreadily available, in combined form, as a commercial unit.

Turning attention next to the valve member, or spool, 12 in part B ofthe valve, and the cylindrical insert which cooperates with it, it willbe noted that the construction is the same and, accordingly,corresponding elements have been designated by corresponding referencenumerals with the addition of subscript a. The spool is actuated by adiaphragm 40a under the control of a pilot valve and solenoid 43a, 44a.

In accordance with the present invention the valve housing 10 includes asupply line chamber 51, an intermediate chamber 52, a control linechamber 53 and an exhaust line chamber 54. The seat 23 of the firstmovable valve member is interposed between the fluid supply line chamber51 and the intermediate chamber 52 whereas the seat 23a, associatedwiththe second valve member is interposed between the intermediatechamber 52 and the control line chamber 53 so that the pressure fluidentering at the chamber 51 is conducted past the valve seat 23 then pastthe valve seat 23a before passing into the control line. Stated insimple terms, the inlet ports of the two valve members are connected inseries with one another. Since, before pressurized fluid can be passedto the control line 14, such fluid must flow in succession past theseats 23, 23a, both of the valve members I1, 12 must be in theiractivated or on positions, and the failure of either valve element to bein such position revents pressure from passing into the control line.

Further in accordance with the invention the valve seats 24, 24a areboth directly interposed between the control line chamber 53 and theexhaust line chamber 54 so that when the valve members are in theirupper position shown in FIG. 1 the exhaust line is sealed off, but whenvalve members are in their lower or off position, pressurized fluid inthe control line 14 is free to escape, or be vented, past both of theseats 24, 24a into the exhaust line 15. It is the latter condition whichis illustrated in FIG. 2 which shows the diaphragms 40, 40a collapsedand with the valve members 8, 12 lowered by gravity to seal off theupper, or inlet seats 23, 23a while opening both of the exhaust seats24, 24a.

Since the pressurized fluid from the control line 14 is free to escapesimultaneously past both of the seats 24, 240, such seats areeffectively connected in parallel with one another. The advantage ofthis is that in the event that either of the valve members 1 1, 12should fail to respond, or drop, from the on" position shown in FIG. 1to the oil position shown in FIG. 2, the pressurized fluid in thecontrol line 14 will nevertheless be directly and fully vented to theexhaust line 15 producing an immediate drop in the pressure of thecontrol line to zero. Note that the term directly vented has beenemployed which makes it clear that pressurized fluid from the controlline is directly vented past a single valve seat into the exhaust line.This is to be contrasted with prior series valve systems which didprovide positive cut off of pressurized fluid but which also requiredthat the venting occur in series relation past two successive valveseats presenting an obstruction to the flow of fluid and a delay in theventing cycle.

The additional safety provided by the present valve assembly will beapparent upon inspection of FIGS. 3 and 4 which show the movable valvemembers respectively stuck in the upper or on" position.

Thus focusing attention upon FIG. 3 the second portion B of the valve,formed by the valve member 12, is shown stuck in open position. Suchsticking may be either due to the physical sticking of the valve member12 within the housing 10, to the sticking of the pilot valve 43a orsolenoid 44a which controls it, or to an electrical malfunction whichfails to turn ofl' the solenoid 44a upon command. In short, anymalfunction which causes the valve member 12 to remain in its upper oron position when it should be turned off is covered by the general termsticking. In any event, since the inlet valve seats 23, 23a areconnected, as shown, in series with one another, the fact that the valvemember 11 has responded to the command to drop and is in its lowerposition insures that the flange 21 is seated against the seat 23thereby precluding any flow of pressurized fluid from the fluid supplyline 13 into the control line 14. Moreover, since the valve member 11has, on command, dropped to its lower position, flange 22 has separatedfrom seat 24 providing a large and direct connection between the controlline chamber 53 and the exhaust line chamber 54 for immediate andcomplete venting of pressure fluid from the control line 14 into theexhaust line 15. Thus the control line 14 is reliably and completelyvented to turn ofithe clutch of the power press or other controlledmachine, and to set the brake, notwithstanding the factthat one half ofthe valve assembly has failed to respond to command.

Equal protection is provided in the event that the valve member 11 failsto respond as shown in FIG. 4. In this figure the valve member 11 isstuck, either by reason of physical sticking within the housing or byreason of the fact that the pilot valve which controls it has failed torespond. This leaves the seat 23 uncovered so that pressure fluid mightenter, but the fact that the valve member 12 has dropped in accordancewith command has sealed the valve seat 23a, which is in series with theseat 23, so that pressure fluid is positively blocked against enteringthe control line 14. Also, while sticking of the valve member 11 in itsupper position has failed to uncover the exhaust seat 24, the fact thatthe valve member 12 has dropped opens the valve seat 240 to permitimmediate and complete venting of pressure fluid from the control line14 through control line chamber 53 and into exhaust line chamber 54 tothe exhaust line 15. Accordingly the pressure in the control line 14drops to zero to turn off the clutch and set the brake.

The press, in view of the safety factor provided by the aboveseriesparallel assembly, could be operated indefinitely with one side ofthe valve in stuck condition without the operator being aware.Therefore, detector switches 61, 62 are provided responsive to the axialmovements of the valve members and suitably connected to the presscontrol circuitry in such a way as to prevent the next succeeding oncommand if either valve fails to respond to the off command. It is,however, unnecessary to show the press control circuitry in order toillustrate the function of the switches and this function may beillustrated by assuming that the switches are connected to individuallamps 63, 64. Where such lamps are employed flashing of each lamp duringa single press cycle will serve to assure the operator that both sidesof the valve assembly are fully operative, whereas failure of one of thelamps to flash, either by remaining on, or by remaining off, denotesthat one side of the valve is stuck so that the press may be shut downuntil the situation is remedied. In short, while the series-parallelvalving arrangement prevents a dangerous malfunction of the press uponfailure of a portion of the valve, it is not intended that the presscontinue to be operated unless both portions of the valve assembly arein working order.

The invention has been discussed in connection with control of a powerpress wherein failure of the slide to come to rest at the top of thestroke may create hazardous conditions for the operator and the pressitself. It will be apparent, however, that the present valve is notlimited to use with a power press, and it will be understood that thevalve assembly has general utility wherever it is necessary to control apotentially hazardous piece of mechanism by pressure or complete lack ofpressure in a control line.

While the construction has been discussed above relating the valve seatsto the chambers 51-54, it may be helpful, in understanding theconstruction, to consider that the first portion A of the valve is adouble two-way valve having a total of four ports communicating with therespective chambers 51-54 while the second portion B of the valve is athree-way valve connected at its ends to chambers 52, 54 but with all ofthe central ports being connected to the control line chamber 53.

I claim as my invention:

1. A safety valve assembly for supplying pressurized fluid from a supplyline to a clutch and brake control line to energize the clutch andde-energize the brake and for alternatively exhausting fluid from thecontrol line to an exhaust line to deenergize the clutch and energizethe brake which comprises means defining a fluid supply line chamber andan intermediate chamber as well as a control line chamber and an exhaustline chamber, a first valve having a movable valve member cooperatingwith first and second seats, the first seat being normally closed andthe second seat being normally open and having an actuator foractivating such valve member, a second valve having a movable valvemember cooperating with third and fourth seats, the third seat beingnormally closed and the fourth seat being normally open and having anactuator for activating such valve member, the first seat beinginterposed between the supply line chamber and the intermediate chamberand the third seat being interposed between the intermediate chamber andthe control line chamber so that such seats are effectively in serieswith one another with pressurized fluid being passed successivelythrough the first and third seats from the supply line chamber to thecontrol line chamber when the valve members are simultaneously activatedby the actuators, the second and fourth seats being both interposedbetween the control line chamber and the exhaust line chamber with suchseats being efiectively in parallel with one another so that in theevent either one of the movable valve members, upon deactuation, sticksin its activated position (a) flow of pressurized fluid from the supplyline will be cut off and (b) direct access for exhausted fluid will beprovided from the control line to the exhaust line for insuring that theclutch and brake are in a safe condition.

2. The combination as claimed in claim 1 in which the movable valvemembers are each in the form of a spool having spaced, inwardly facingflanges cooperating with opposed outwardly facing valve seats with thespools being movable-endwise through a limited displacement foralternative closing of the valve seats.

3. The combination as claimed in claim 2 in which the valve seatscooperating with a given spool are formed at the respective ends of acylindrical insert having lateral openings formed therein.

4. The combination as claimed in claim 1 in which the housing means isunitary enclosing all of said chambers and seats and with means forguiding the movable valve members into seated condition with respect tothe seats.

5. A safety valve assembly for supplying pressurized fluid from a supplyline to a clutch and brake control line to energize the clutch andde-energize the brake and for alternatively exhausing the fluid from thecontrol line to an exhaust line to de-energize the clutch and energizethe brake, which comprises a first valve in the form of a double two-wayvalve having first and second valve seats defining a total of fourports, the seats being engaged by a valve member movable between limitpositions for closing the seats alternatively, a second valve in theform of a three-way valve having third and fourth valve seats defining atotal of three ports, the seats being engaged by a valve member movablebetween limit positions for closing the seats alternatively, separateactuating means for activating the valve members, means forinterconnecting the ports associated with the first and third valveseats in series so that when the valve members are both activated,pressurized fluid is conducted in succession past the first and thirdvalve will remain open to provide direct escape of exhausted fluid fromthe control line.

6. The combination as claimed in claim 5 in which means are provided forsignalling the sticking of one of the valve members.

1. A safety valve assembly for supplying pressurized fluid from a supplyline to a clutch and brake control line to energize the clutch andde-energize the brake and for alternatively exhausting fluid from thecontrol line to an exhaust line to de-energize the clutch and energizethe brake which comprises means defining a fluid supply line chamber andan intermediate chamber as well as a control line chamber and an exhaustline chamber, a first valve having a movable valve member cooperatingwith first and second seats, the first seat being normally closed andthe second seat being normally open and having an actuator foractivating Such valve member, a second valve having a movable valvemember cooperating with third and fourth seats, the third seat beingnormally closed and the fourth seat being normally open and having anactuator for activating such valve member, the first seat beinginterposed between the supply line chamber and the intermediate chamberand the third seat being interposed between the intermediate chamber andthe control line chamber so that such seats are effectively in serieswith one another with pressurized fluid being passed successivelythrough the first and third seats from the supply line chamber to thecontrol line chamber when the valve members are simultaneously activatedby the actuators, the second and fourth seats being both interposedbetween the control line chamber and the exhaust line chamber with suchseats being effectively in parallel with one another so that in theevent either one of the movable valve members, upon deactuation, sticksin its activated position (a) flow of pressurized fluid from the supplyline will be cut off and (b) direct access for exhausted fluid will beprovided from the control line to the exhaust line for insuring that theclutch and brake are in a safe condition.
 2. The combination as claimedin claim 1 in which the movable valve members are each in the form of aspool having spaced, inwardly facing flanges cooperating with opposedoutwardly facing valve seats with the spools being movable endwisethrough a limited displacement for alternative closing of the valveseats.
 3. The combination as claimed in claim 2 in which the valve seatscooperating with a given spool are formed at the respective ends of acylindrical insert having lateral openings formed therein.
 4. Thecombination as claimed in claim 1 in which the housing means is unitaryenclosing all of said chambers and seats and with means for guiding themovable valve members into seated condition with respect to the seats.5. A safety valve assembly for supplying pressurized fluid from a supplyline to a clutch and brake control line to energize the clutch andde-energize the brake and for alternatively exhausing the fluid from thecontrol line to an exhaust line to de-energize the clutch and energizethe brake, which comprises a first valve in the form of a double two-wayvalve having first and second valve seats defining a total of fourports, the seats being engaged by a valve member movable between limitpositions for closing the seats alternatively, a second valve in theform of a three-way valve having third and fourth valve seats defining atotal of three ports, the seats being engaged by a valve member movablebetween limit positions for closing the seats alternatively, separateactuating means for activating the valve members, means forinterconnecting the ports associated with the first and third valveseats in series so that when the valve members are both activated,pressurized fluid is conducted in succession past the first and thirdvalve seats, means for interconnecting the ports associated with thesecond and fourth valve seats in parallel so that when the valve membersare both deactuated, exhausted fluid is conducted in parallel past thesecond and fourth valve seats and so that in the event one of the valvemembers, upon being deactuated, sticks in its activated position atleast the second or fourth seat will remain open to provide directescape of exhausted fluid from the control line.
 6. The combination asclaimed in claim 5 in which means are provided for signalling thesticking of one of the valve members.